Related Field
The present invention relates to an elongated fluid actuator arrangement according to the preamble of claim 1.
The present invention concerns the industry using hydraulic and/or pneumatic actuators for different types of applications and also concerns the manufacture industry producing such arrangements.
The invention is not limited thereto, but can also be used for replacing electrical actuator arrangements and can be adapted for application of a wide range of different types industries.
Description of Related Art
There is a desire to provide an elongated fluid actuator arrangement that reliably could distribute proper control functionality regarding force and motion rate of the piston rod member.
Current technology as published uses elongated fluid actuator arrangements that are designed with specific features for achieving desired pressure performance and pressure distribution for different motion rates and actuating forces. This may imply overweight and over-dimension materials.
Current technology also often uses a centrally controlled operation for controlling maximum motion rate and force of the piston rod member by means of regulating the fluid flow and pressure of the fluid supply device. Such centrally controlled feeding of fluid may make such arrangement ineffective.
U.S. Pat. No. 4,506,867 discloses a jacking apparatus for effecting motion of loads by means of two double-acting hydraulic cylinders for providing increased force of a power stroke. Hydraulic fluid pressure is controlled to a predetermined flow rate to the hydraulic cylinders for increasing the speed of a repositioning stroke of the apparatus.
U.S. Pat. No. 3,220,317 discloses a servo system having a hydraulic motor system with two pistons arranged in tandem for each motor. The system uses two motors connected in parallel so that their motions are in fixed proportions and their forces are added. The system may also be arranged with the motors in series so that forces are in fixed proportions and that motion is added.